Fair-lead structure

ABSTRACT

The invention relates to a fair-lead structure including an elongated hollow jib which is journaled from the supporting frame at a point intermediate its ends for both swivel and transverse movement.

United States Patent Inventor Appl. No.

Filed Patented Assignee Frank L. Lawrence Vancouver, British Columbia, Canada 785,502

Feb. 4, 1969 June 29, 1971 B.C. Gem-works Ltd.

North Surrey, British Columbia, Canada Continuation-impart of application Ser. No. 649,635, June 28, 1967, now Patent No. 3,458,153.

FAIR-LEAD STRUCTURE 3 Claims, 7 Drawing Figs.

................................................ r. 242/l57.l, 254/186, 254/190 US. Cl

511 1nt.C1 B65h 57/00 [50] Field of Search. 254/190, 150, 186;242/158, 157.1

[56] References Cited UNITED STATES PATENTS 1,917,640 7/1933 Fairbanks 242/157.1 2,453,184 11/1948 Berry 242/158 Primary Examiner-Harvey C. Hornsby Attorney-Seed, Berry & Dowrey ABSTRACT: The invention relates to a fair-lead structure including an elongated hollow jib which is journaled from the supporting frame at a point intermediate its ends for both swivel and transverse movement.

PAIENIED JUN29 IQH SHEET 1 BF 3 FRANK L. LAWRENCE INVENTOR.

FIG

ATTORNEYS PATENTEU JUN29 I971 SHEET 3 OF 3 FRANK L. LAWRENCE INVENTOR.

ATTORNEYS FAIR-LEAD STRUCTURE This application is a continuation-in-part of U.S. Pat. application No. 649,635, filed June 28, 1967, now U.S. Pat. No. 3,458,153.

By far the majority of the level-wind structures heretofore devised have incorporated what is commonly known as a diamond screw drive to impart reciprocatory movement to a traverse head. Diamond-screw" drives will not stand up under excessive thrust loadings such, for example, as those to which the drums of a logging yarder are subject. The present invention aims to provide an efficient level-wind structure capable of withstanding high levels of torque loading, which is not adversely affected where required to operate under adverse weather conditions, and which exhibits only minimal wear under long and continual usage.

In the accompanying drawings: 7

FIG. 1 is a fragmentary side elevational view, with parts broken away and in section, to illustrate a yarder having a level-wind structure employing preferred teachings of the present invention.

FIG. 2 is a fragmentary top plan view thereof.

FIG. 3 is a fragmentary transverse vertical sectional view drawn to an enlarged scale on line 33 of FIG. ll.

FIG. 4 is a fragmentary enlarged scale view detailing the control valve and associated mechanism shown in FIG. 3.

FIG. 5 is a fragmentary vertical sectional view drawn to an enlarged scale on line 5-5 of FIG. 3.

FIG. 6 is a fragmentary detail elevational view drawn to an enlarged scale,

FIG. 7 is a fragmentary longitudinal vertical sectional view drawn to an enlarged scale on line 7-7 of FIG. 2.

DESCRIPTION OF INVENTION Referring to said drawings, a fabricated framework for a yarder is designated by the numeral 10, and denoted by llll is one of the several cable-winding drums usual to a yarder. A drive is passed by a chain 12 to the drum, and such drive desirably includes a reversible hydraulic motor (not shown) having its pump driven by a diesel engine or other suitable power plant. The cable C is led to and from the drum by passing through a hollow jib which extends longitudinally of the yarder, being trained over a respective one of two fair-lead sheaves 13 and 14 at each of the two ends thereof. The jib is universally journaled for both swing and swivel movement in the frame of the yarder by a ball-and-socket joint, the ball component 15 being formed upon the jib and the socket component being formed in part by a fixed ring 16 and in part by a removable keeper ring 17 which is bolted in place. The socket is located in the longitudinal median plane of the drum above and at a distance of say 12 or so therefrom. A long arm 18 of the jib extends inwardly toward the drum and overhangs the near side of the latter. A short arm 19 of the jib extends outwardly. Sheave 13 receives its mounting from the short arm, being journaled upon a cross pin 20 in an offset position placing its perimeter tangent to the swivel axis of the jib.

The hollow stem of a block 23 is swiveled in the free end of said long arm 18. Sheave 14 receives its mounting from the block, being journaled upon a cross pin 24 in an offset position placing its perimeter tangent to the swivel axis of the block.

The free end of the jibs long arm is attached by a pivot pin 25 to the upper free end of a powered third-order rocking lever 26 which establishes for said free end a reciprocating travel moving along a prescribed path the end limits of which coincide with perpendiculars raised from the two ends of the winding surface of the drumv In compensation of the compounded are along which the free end of the arm 18 travels, the rocker fulcrum for said lever 26 is a ball and socket, denoted at 28. The power for reciprocating the lever is a double-acting hydraulic jack 29 having one end pivoted at 30 to the frame of the yarder and the other end pivoted at 311 to the lever. A valve 32 governs the jack, the valve being of the usual character having a valve spool 33 working within a chest, with the particular end of the jack to which hydraulic fluid is fed and the rate of the fluid flow being determined in the respective instance by the positionright or left of center-occupied by the spool and the degree of movement from said centered neutral location. I

Such movement of the spool within the chest is regulated by means including a rotary cam 34, the cam being interconnected with the drum by a reduction drive so as to complete a half revolution while the drum is making the turns necessary to develop one full wrap of cable. The number of turns required for a full cable wrap is of course determined by the cable diameter. In instances where it may be desired to adapt the winding drum to different sizes of cable, it becomes necessary only to modify the reduction ratio and this is or may be accomplished by employing in the reduction drive an endless chain 35 trained over a selected one of several sets of sprocket wheels, as 36-37, each correlated to a given cable diameter. The reduction drive is here shown as including, with the chain and its sprocket wheels, a pinion 40 meshing a gearwheel 41, and a pinion 42 meshing a gearwheel 43, the cam 34 being made to turn in unison with the latter gearwheel.

The profile configuration of the cam is so developed that a roller 45, carried by a third-order lever 46 and tracking on the perimeter of the cam, moves radially thereof at a uniform speed inwardly during one-half the turn of the cam and outwardly during the other half. The lever 46 is fulcrumed at 47 and acts through a rack-and-pinion connection S051 to govern the rotation of a reciprocally movable sprocket wheel 52 serving a motion-transfer function. Attached by one of its ends to this sprocket wheel is a chain 53 taking a right-angle bight midway of its length over a floating sprocket wheel 54 and having its other end attached to the rocking lever 26. The floating sprocket wheel is carried by a third-order lever 55 fulcrumed at 56 to the frame of the yarder and attached by a link 57 to the spool 33 of the control valve 32.

Spool 33 is shifted, against or with the applied force of a spring 60, in either a left-to-right or a right-to-left direction (as viewed from the vantage point of FIG. 3) for respectively causing hydraulic fluid to be charged to the right-hand end or the left-hand end of the hydraulic jack. Greater or lesser tensions of the chain are responsible and act upon the floating sprocket wheel to dictate the direction and the extent of the spools shift. When the rocking lever is moving in a left-toright direction, the spool has moved left of center. An increase in the tension of the chain occurs should a volume of oil be supplied to the jack causing the rocking lever to overrun a predetermined position prescribed therefor for any given period of the cable-wrapping cycle. This increase of tension draws the spool toward center, which reduces the oil flow. A lag of the rocking lever when moving in said left-to-right direction decreases chain tension with a responsive spring-influenced movement of the spool from center, which increases the flow. When the rocking lever is moving in the opposite direction, namely right to left, the spool will have then been moved right of center. For this direction of travel an increase of tension occurs by a lag of the rocking leg, and a decrease occurs by a overrun. The spool shifts from center and toward center in the respective instance, which perforce causes an increase and a decrease, respectively, in the oil flow.

There is provided in the level-winding system a release means for the chain 53 which automatically slacks off the chain should the same be tensioned above a predetermined ceiling point. A situation in which this high tension could occur is where an operator, shutting down overnight, neglects to slack off the cable. Should the cable be left taut the possibility arises that a log, snag or the like laying against the cable at a point close-in to the yarder can exert upon the cable a lateral force of sufficient magnitude that the jib, responsively torquing about a vertical axis, snaps the chain. The release comprises a shoe 61 pivoted at 62 to the leg so as to rock about a horizontal axis extending transverse to the chain. The chain seats in a groove extending longitudinally of the shoe and is connected at 63 to the free end ofa trip lever 64 pivoted at 65 to the shoe. The trip lever is yieldingly urged in a forward direction by a spring 68, catching under a lip 66 formed upon a bracket 67 welded to the rocking leg.

It is believed that the invention will have been clearly un derstood from the foregoing detailed description of my now' preferred illustrated embodiment Changes in the details of construction may be resorted to without departing from the spirit of the invention and it is accordingly my intention that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admits.

The embodiments of the invention in which an exclusive property or privilege I claim are defined as follows:

1. ln fair-lead structure, a frame, a hollowjib joumaled from the frame at a point intermediate the ends of the jib for both swivel and transverse swing movement about that point, a fairlead sheave carried by the jib at one end thereof, a block swivel mounted in the other end of the jib, and a fair-lead sheave carried by the block, guide means being provided constraining the ends of the jib to swing movement in prescribed arcs.

2. The structure of claim 1 in which the swivel-and-swing journal is provided by a ball-and-socketjoint, the guide means being comprised of a radius arm attached by its free end to one end of thejib.

3. ln a fair-lead structure, a mount, a hollow jib journaled from the mount at a point intermediate the ends of the jib for transverse swing movement, a respective fair-lead sheave carried by the jib at each of its two ends for independent swivel motion about the center of the jib as an axis and functional to feed cable to and from the hollow center of the jib, and guide means operatively interconnected with one end of the jib and constraining the same to swing travel along a prescribed path. 

1. In fair-lead structure, a frame, a hollow jib journaled from the frame at a point intermediate the ends of the jib for both swivel and transverse swing movement about that point, a fairlead sheave carried by the jib at one end thereof, a block swivel mounted in the other end of the jib, and a fair-lead sheave carried by the block, guide means being provided constraining the ends of the jib to swing movement in prescribed arcs.
 2. The structure of claim 1 in which the swivel-and-swing journal is provided by a ball-and-socket joint, the guide means being comprised of a radius arm attached by its free end to one end of the jib.
 3. In a fair-lead structure, a mount, a hollow jib journaled from the mount at a point intermediate the ends of the jib for transverse swing movement, a respective fair-lead sheave carried by the jib at each of its two ends for independent swivel motion about the center of the jib as an axis and functional to feed cable to and from the hollow center of the jib, and guide means operatively interconnected with one end of the jib and constraining the same to swing travel along a prescribed path. 